I did this mod over the weekend and am very happy with both the sound and the extra responciveness at part throttle. To do it you don't even need to pull the vaccume line. just kink it and put a zip tie arround the kink. No chance of vaccume loss and your good to go.

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2007 X3 Silver Gray, Gray Leather, Soprt, Premium, 19" 2MM wheels, Xenons, Self Installed Sirius